Two important variables that are often not measured online in Chinese hamster ovary (CHO) cell cultures are cell number concentration and culture viability. We have developed an automated flow cytometry system that measured the cell number concentration, single cell viability based on propidium iodide (PI) exclusion, and single cell light scattering from bioreactor samples every 30 min. The bioreactor was monitored during batch growth, and then the cell number concentration was controlled at a set point during cytostat operation. NH4Cl was added during steady state operation in cytostat mode to monitor the transient cell population response to adverse growth conditions. The automated measurements correlated well to cell concentration and viability determined manually using a hemacytometer. The described system provides a method to study mammalian cell culture physiology and dynamics in great detail. It presents a new method for the monitoring and control of animal cell culture.
Bibliographical noteFunding Information:
We thank the National Science Foundation for supporting this work (BES 0109383). J. Kacmar was a recipient of a NIH training grant fellowship in biotechnology.
- Automated flow cytometry
- Bioreactor control
- Bioreactor monitoring
- Mammalian cell culture
- Single cell heterogeneity